Pre-crash safety (PCS) systems that reduce or prevent collision damage between an obstacle (target) and an own vehicle have been produced. The obstacle is another vehicle, a pedestrian, a road structure, or the like present ahead of the own vehicle that has been detected by a target detection apparatus, such as an imaging apparatus or a radar apparatus. In PCS, a collision prediction time (time to collision [TTC]) is determined based on a relative distance between the own vehicle and the obstacle, and a relative speed or a relative acceleration. The collision prediction time is an amount of time until a collision occurs between the own vehicle and the obstacle. Based on the collision prediction time, a driver of the own vehicle is notified of approach by a warning apparatus, or a braking apparatus of the own vehicle is operated.
However, when axial misalignment in which an attachment angle of the target detection apparatus becomes tilted occurs, an obstacle that is not actually positioned ahead of the own vehicle is erroneously detected as being ahead of the own vehicle. The axial misalignment of the target detection apparatus may occur as a result of vibrations applied during vehicle traveling, an occurrence of light impact on the own vehicle, and the like.
Therefore, since the past, axial misalignment detection for the target detection apparatus has been performed. For example, when a radar apparatus is used as the target detection apparatus, angle misalignment information of the radar apparatus is acquired from a movement trajectory of a road-side object detected by the radar apparatus. Then, as a result of a history of the angle misalignment information being statistically processed, an axial misalignment angle of the radar apparatus is calculated (refer to PTL 1).